In general, a composition for interior and exterior deco parts of vehicles is mainly composed of polypropylene (PP) and a polypropylene-based resin composition that includes an impact modifier and an inorganic filler has been used.
Before the middle of 1990's at which an ethylene α-olefine copolymer that is polymerized by applying a metallocene catalyst was developed, as the material of the interior and exterior decos of vehicles, particularly, a material of a bumper cover, a polypropylene-based resin composition which is mixed with EPR or EPDM as an impact modifier was mainly used. However, after the ethylene α-olefine copolymer that is manufactured by the metallocene catalyst has been used, as an impact modifier, the ethylene α-olefine copolymer starts to be used, and recently, the ethylene α-olefine copolymer has been mainly used. The reason for this is that the polypropylene-based complex material using this has uniform properties such as impact strength, elasticity, bending strength and the like, and good shapability, and is low-priced.
Since polyolefine that is synthesized by the metallocene catalyst is uniformly controlled in terms of molecular structure as compared to the Ziegler-Natta catalyst, it has a narrow molecular weight distribution and excellent mechanical properties. Since in the case of the low density ethylene elastomer which is polymerized by metallocene catalyst, the α-olefine copolymerization monomer is relatively uniformly inserted into the polyethylene (PE) molecule as compared to the use of the Ziegler-Natta catalyst, while low density rubber properties are maintained, excellent other mechanical properties are ensured.